CN105703992B

CN105703992B - Variable data rate control method

Info

Publication number: CN105703992B
Application number: CN201510931653.6A
Authority: CN
Inventors: 唐纳德·穆雷·特勒斯; 丹尼尔·卡默曼
Original assignee: Schneider Electric Australia Pty Ltd
Current assignee: Schneider Electric Australia Pty Ltd
Priority date: 2014-12-15
Filing date: 2015-12-15
Publication date: 2020-05-01
Anticipated expiration: 2035-12-15
Also published as: PL3035605T3; AU2015268688B2; HUE043616T2; NZ715112A; TR201904244T4; DK3035605T3; HRP20190925T1; EP3035605A1; EP3035605B8; MY177536A; AU2015268688A1; ZA201509046B; ES2730021T3; CN105703992A; HK1224465A1; EP3035605B1; PT3035605T; TWI672021B; TW201633749A

Abstract

The application discloses a variable data rate control method. In a method of communicating data in a packet switched baseband signaling communication network having a plurality of devices, wherein each device comprises at least a data transmitter and a data receiver capable of transmitting and receiving frames comprising payload data at least at a first data rate, said method comprising the steps of: including data at the first data rate in a portion of the frame indicating that payload data to be subsequently transmitted in the frame is to be transmitted at a second data rate higher than the first data rate; and transmitting a keep medium busy signal at the first data rate during transmission of the payload data at the second data rate.

Description

Variable data rate control method

Technical Field

The present disclosure relates to a method of enabling a change in transmission effective bandwidth in a packet switched baseband signaling communication network.

Background

Typical electrical control systems for home and building installations include a large number of electrical devices and/or electrically controlled devices designed to be controlled, such as: electrical switches and sockets; various types of electrical loads (e.g., lighting, heating, cooling, and various electrically powered devices); and protective devices such as micro circuit breakers, residual current circuit breakers, fuses and the like.

The control system in such installations comprises one or more devices including transceiver devices associated with one or more of the above electrical devices, the transceivers typically being coupled in parallel via a communication medium. For reasons of simplicity and cost, typically the communication medium comprises means of broadcast datagrams (signals) on two wires. Power may also be carried on the two conductors or separately provided. The two wire approach may have shielded or unshielded twisted pair wires. Various topologies may be used for the communication medium, such as bus, star, ring, mesh, and/or hybrids thereof.

Each device in the network comprises: a transceiver for receiving and transmitting data signals; a computer device for voluntarily receiving and transmitting data according to programs stored therein and in the storage means to maintain various data (e.g., the status of other devices in the network); and control circuit means for controlling electrical devices (e.g., lights, switches, and electrical loads) associated therewith. Each device in the network is adapted and arranged to exchange data signals via a communication medium, in one example a two-wire approach.

By linking various devices, different equipment associated with each device can be controlled and managed, each device being controlled independently of the other devices. Information exchange between devices is an important factor in controlling the devices on the network, and it is a typical way to form the exchange information digitally for control and management control.

It is desirable to design digital signal transmission to minimize information exchange errors at a data rate best suited to minimize information exchange errors. However, communication media have an inherent upper bandwidth limit for the amount of digital information that can be carried at any time with reasonable reliability. Thus, there are many digital transmission techniques and protocols that can be used to share the available bandwidth of a communication medium among numerous various types of devices distributed over a network.

Digital data communication techniques used in these networks are known as carrier sense multiple access with collision detection (CSMA/CD) and are most often used when data communication is performed between one of many devices distributed on a physical network. Another improvement of the CSMA/CD mechanism is to include some form of Collision Avoidance (CA) so that the inevitable collisions of digital data frames do not result in a loss of available transmission time nor data.

CSMA/CD CA does not require any central coordination, so it is well suited for home building electrical control systems that use fixed digital data exchange rates to communicate information between distributed intelligent devices such as those described above. However, in bandwidth constrained networks using, for example, the type of two-wire medium described above, CSMA/CD need not be optimally configured to optimally use the available transmission bandwidth throughout the transmission of a data frame.

The available bandwidth of the communication medium that conveys digital information between devices depends on various factors such as the signaling mechanism used, the available signal processing power in the devices, and network topology factors like overall length, the number of attached devices, the type and impedance of the cable, and the load the devices impose on the network. Restrictive choices of limits for all of these factors, as well as others, may be used to define the selected signaling rate.

The collision detection and collision avoidance mechanisms employed on CSMA communication media may require: the signaling rate chosen to ensure reliable collision detection and collision avoidance in broadcast listening of the worst case network topology is less than the actual unicast bandwidth available between two devices on the network.

The broadcast bandwidth of the CSMA communication medium may be defined as the transmission signaling rate at which high reliability reception may be achieved by all devices given the chosen network topology constraints without collision detection and collision avoidance.

The actual unicast bandwidth available from one device on the network to another device on the network (point-to-point) may be the same as, or much larger than, the broadcast bandwidth. In addition, due to factors such as the physical characteristics of the network and the relative locations of the two communication devices, and other factors, the actual bandwidth may not be symmetric, i.e., it may be faster in one direction than the other.

The network uses a predetermined data rate that ensures that all devices can communicate with other devices regardless of where they are in the network, thereby eliminating the possibility of using higher data rates to accommodate data that is considered an immutable constraint on the physical system that makes up the network.

Disclosure of Invention

It is proposed that a protocol may be provided which may use existing network bandwidth limitations for transmission during at least a bus contention (content) period (note that the term bus contention period herein refers to a period of time during which a collision detection and collision avoidance mechanism is active), following which the remainder of the data should be collision free, but which allows a signalling rate to be selected for the payload data to be transmitted within a frame following the bus contention period, thereby allowing different data rates to be used in portions of the frame.

In addition to the possible advantages obtained by optimally utilizing available but unused network bandwidth capabilities in different parts of the transmission of frames, any protocol improvements should be compatible with existing installed devices and associated controllable configurations, so that, without the cost burden associated with replacement or upgrade of existing devices or associated controllable configurations, systems present in the network can be upgraded at the convenience of the network owner by adding one or more devices and associated controllable configurations that can transmit and receive the original standard (typically low) data rate and updated (typically higher) data rate transmissions.

A non-limiting feature of the present disclosure provides a data communication protocol in a packet switched baseband signaling communication network having a plurality of devices, wherein each device includes at least a data transmitter and a data receiver capable of transmitting and receiving frames including payload data at least a first data rate, the method comprising the steps of: transmitting, by a transmitter of an apparatus of the plurality of apparatuses, data at a first data rate in a portion of a frame indicating that payload data to be subsequently transmitted in the frame is to be transmitted at a higher data rate than the first rate; and during transmission of payload data at the second data rate, transmitting a keep medium busy signal at the first data rate indicating to other devices that the network is in use.

Throughout this specification and the claims which follow, unless the context requires otherwise, "comprise" and variations such as "comprises" and "comprising" will be understood to imply the inclusion of a stated feature or group of features but not the exclusion of any other feature or group of features.

The reference to any background or prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that background or prior art forms part of the common general knowledge.

Other embodiments may be suggested and described that may be included within the disclosure, but they may not be shown in the drawings, or alternative features of the disclosure may be shown in the drawings and not described in the specification.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. For a hardware implementation, the processes may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. A software module, also referred to as a computer program, computer code, or instructions, may comprise a multitude of source or target code segments or instructions and may reside on any type of computer-readable medium, such as RAM memory, flash memory, ROM memory, EPROM memory, registers, hard disk, a removable disk, a CD-ROM, a DVD-ROM, or any other form of computer-readable medium. Alternatively, the computer readable medium may be integral to the processor. The processor and the computer readable medium may reside in an ASIC or related device. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.

Those skilled in the art will appreciate that the embodiments are not limited in their application to the particular uses described. The present embodiments are not limited to their preferred embodiments with respect to the specific elements and/or features described or illustrated herein. It will be understood that various modifications may be made without departing from the disclosed principles. Accordingly, the embodiments are to be understood as encompassing all modifications within their scope.

Drawings

FIG. 1 shows a basic layout of a plurality of devices arranged in a network interconnected by a pair of wires;

FIG. 2 shows a CSMA/CD CA digital data frame including acknowledgements;

fig. 3 illustrates a variable data rate (high speed) frame including an acknowledgement according to an embodiment;

fig. 4 shows details of a variable data rate (high speed) setting block for a variable data rate (high speed) frame according to an embodiment;

fig. 5 shows details of a variable data rate (high speed) payload block for a variable data rate (high speed) frame according to an embodiment;

FIG. 6 shows a timing diagram for a slot containing variable data rate (high speed) data being transmitted illustrating the incorporation of data transmitted at a standard data rate (low speed) in the slot for use as a hold medium busy signal and payload data transmitted at a higher data rate than that used during a bus contention period, in accordance with an embodiment;

FIG. 7 shows an example of a high speed control block; and

fig. 8 shows an example of a negative acknowledgement block;

fig. 9 shows an example of signaling of a negative acknowledgement from an apparatus to a transmitting apparatus; and

fig. 10 shows an example of the result of receiving one of the possible NACK responses, in which case the transmission best for the payload may be 24 times the standard data rate, in another example 8 times the standard data rate.

Detailed Description

It would be useful to be able to selectively replace or upgrade devices at minimal cost and with minimal inconvenience to have a network operate to allow for an increase in the data rate of data exchange between new or upgraded devices on the network with increased demand for data due to changing commands.

There are times when it may be advantageous or highly important to upgrade the firmware and/or configuration used by one or more devices for many other reasons or needs, as updates may need or be sent over existing networks, as out-of-band interfaces may not be available or convenient. In one example, the firmware of devices on home and building networks inevitably needs to be updated to improve the security of the devices, in another example, controlled devices on the network need to be updated, e.g., firmware to perform new functions or configuration parameters of the devices need to be changed. The data comprising the updates will need to be sent over the network at the normal signalling rate which is typically appropriate for the control functions of the devices associated with a device and which are used to control those devices. The data rates for these home and building networks are typically low (compared to most dedicated computers, computer communication data rates, or even wireless data communication rates), and small amounts of data are typically communicated between devices, emphasizing accuracy over data rates because of the high level or reliability of the data. However, these are very small amounts of data compared to the amount of data required to perform a firmware update, and as a result, the process of updating one or more devices on the network will result in unacceptably long update times and/or unacceptably high network utilization, potentially resulting in a loss of use of other devices on the network during the firmware update. Once large amounts of data can be transmitted at an acceptably higher data rate, the network can be made available for many previously unforeseen purposes, such as the transmission of audio, video, bulk data, etc.

Communication of data in a packet-switched baseband signaling communication network occurs at a known data rate for the device on the network. The network will have a plurality of devices, each device including at least a transmitter and receiver capable of transmitting and receiving data (sometimes referred to as frames or blocks of data or messages) for all other devices, wherein the baseband signaling for data communication includes a keep-alive medium busy signal emanating from the transmitting device. The keep medium busy signal may take many forms and its primary purpose is to indicate to the other devices that the network is being used by only one transmitting device that transmits the data at a known data rate for reception by one or more other devices.

CSMA/CD (carrier sense multiple access/collision detection) is widely used to determine how network devices in a network communicate data in a message and how to respond in case of collision. Collisions occur when two or more devices on a network attempt to transmit simultaneously on a single physical medium (e.g., twisted pair copper wire or fiber optic cable). This is detected by all participating devices connected to the medium and after a short random and different time interval (sometimes referred to as a back-off delay or contention delay) has elapsed for each device, the device attempts to transmit again. If another collision occurs, the time interval from which the random wait time is selected is gradually increased in a process called exponential backoff, so that one device that needs to transmit can eventually achieve collision-free transmission.

CSMA/CD is a modification of pure CSMA. Carrier sensing refers to the transmission apparatus sensing a carrier (i.e., a waveform carrying one or more signals) before attempting to transmit. I.e. it first tries to detect the presence of a coded signal from another device. If a carrier is listened to, the device waits for the ongoing transmission to complete before starting its own transmission.

Multiple access describes multiple devices transmitting and receiving on a physical medium. Transmissions by one device are typically received in a broadcast fashion by all other devices using the physical medium.

Collision detection is used to improve CSMA performance by terminating transmission by one device whenever a collision is detected and reducing the likelihood of another collision on the next attempt. The techniques for detecting collisions depend on the type of physical medium: in the case of electrical leads, collisions are detected, for example, by comparing the transmitted data with the received data.

CSMA/CD operates at the physical layer, which is the bottom layer in the OSI model used to standardize and simplify definitions on computer networks. This layer defines all physical and electrical specifications for devices used to interface with the network and it only processes data for raw bits that are formed into a frame or message format (which may be different formats).

The main feature of CSMA/CD is that it is easy to implement. This can help make it an important part of the international standard as well as the ethernet system, which is not only a preferred architecture for LANs (local area networks), but is also widely used in short-range networks such as in home and building automation and factory environments.

Some networks, such as the CANbus protocol, may operate at different data rates, but the network requires that all devices connected to the network operate at the same data rate in order to ensure communication. The network data rate is selected to be suitable for installation and, once selected, is unlikely to change. CANbus systems are widely known for use not only in automobiles, but also in home and building automation and factory environments.

We describe herein a method comprising steps that may be used in a protocol that allows for the selection of a relatively high data rate transmission for a particular frame (or message) sent from one device within a network of devices, otherwise operating at a low and generally fixed data rate (mansion referred to as a standard data rate) between all of these devices. Here, the term lower data rate is relative and is intended to inform the reader of differences between data rates that may be generally understood as low data rates or high data rates in the future. In the future, the highest data rate at one time may become the lowest standard data rate available between devices. It is also possible that the data rate used between one apparatus and another apparatus is different from one frame to the next, and it is also possible that the rate at which data is sent from one apparatus to another apparatus is different from the rate at which data is sent back from the other apparatus.

These steps may be incorporated into various frame (message) formats. However, there may be some common aspects including the hold medium busy signal and the idle medium determination process and associated time periods.

In a relatively low data rate baseband communication system, a series of data streams are communicated using a certain coding scheme that defines bit times for a set of fixed time periods. Communication may occur if all members of the network are able to accept the same bit time, which is typically uniform across the communication network where the bit time is an atomic level (minimum period of time to transmit digital data) period for data bit formation and transmission using a particular bit signal encoding scheme, although the overall system can often operate at a variety of different bit times.

A wide variety of information, control and management systems utilizing certain packet-switched communication networks having two-conductor power and communication mediums can be used for as many different applications. In particular, packet-switched networks operating in a level above the network access layer, data link layer and physical layer are being used more often in the residential, commercial building and industrial building construction industries to support building control management systems. In construction and industrial environments, the physical transmission mechanism is the use of a communication medium in a form that is easy to install and relatively inexpensive, and one common form includes pairs of electrical conductors, sometimes in multiple pairs within a housing, and, typically, each of the multiple pairs is twisted. This type of cable is typically certified (CAT 5, CAT5e, CAT 6, etc.) and thus has specific communication characteristics. These wire media facilitate connection and routing for new and existing buildings, and in some configurations, as shown in the schematic diagram in fig. 1, a simple tap line connection may be attached at any point along the conductor pair.

Fig. 1 shows an embodiment of a physical

network comprising conductors

10 and 12 providing media for signal communication to

devices

14, 16, 18 and 20, which are distributed along the length of

conductors

10 and 12 as desired. Power may also be provided on the medium or separately.

The following information is provided to assist the reader in understanding certain terms used in this specification. This information is not intended to be limiting, but rather should assist the reader in this field in combing and applying the disclosed information provided in the specification.

Groove: a period of time during which atomic level transmission may occur. In a byte oriented protocol, this will typically contain one or possibly more bytes of data, as well as any signaling information, such as parity for error detection. C-Bus in one example^TM(Schneider electric (Australia) Ltd. 33Port Wakefield Road, Gepps Cross, SouthAlgoria) System, one slot contains 1 byte (8 bytes)Bit) data and 1 parity bit for odd check.

Frame: a sequence of consecutive slots, containing either active transmission or dummy (note comments below) slots, and including a message and zero or more acknowledgment blocks.

Clock: typically by a signal generated at regular intervals by a device on the network to synchronize communications by the characterization of the start of a new slot. In the exemplary C-Bus system, there is a clock signal and it is generated at a rate of one every 2 ms. It is convenient but not necessary to have a clock and it is not necessary for the methods and arrangements disclosed in this specification.

A dummy groove: empty slots that do not contain a transmission of data.

A dummy block: one or more continuous dummy grooves. In an example C-Bus system, dummy blocks are used to provide information, e.g., a dummy block comprising a single dummy slot may be used to separate different sections of a frame.

Keep medium busy signal: a mechanism to ensure that valid transmissions are distinguished from idle buses. In the exemplary C-Bus system, the free Bus can be distinguished from the transmission of a "0" byte by using an odd check in each slot, which means that there is always at least one valid "1" bit in each slot for any valid transmission. Otherwise, this can be achieved by using a "1" check, i.e. always sending a "1" bit at a defined point in time at the time of sending, but this is less useful because it does not provide the useful error detection information provided by the odd check configuration. In other protocols, there are other ways in which a keep-busy signal may be generated.

Idle medium determination period: the bus exhibits a period of idleness after which the bus is conventionally considered to be actually idle. In an example C-Bus system, an idle medium determination period is defined as a dummy block including two or more consecutive dummy slots.

Bus contention period: a period of time during which one or more devices on the CSMA/CD CA network may transmit simultaneously. In the exemplary C-Bus system, the collision detection mechanism is implemented by each transmitting device monitoring the signal on the Bus in real time as the signal is transmitted. A collision is detected if at any point there is a "1" condition on the bus on which the transmitting device transmits a "0". Then, the collision avoidance mechanism is for the transmitting device that detects a collision to stop transmitting, allowing the other devices that are transmitting "1" at that point to dominate and continue transmitting without error. The last transmitting device that did not detect a conflict is considered the winning or winning device and the device's message will be sent over the network.

In one embodiment, the digital data exchange protocol is preferably of the CSMA/CD CA type, fig. 2 shows a frame, which is a message containing a data payload, wherein in this example the control block 26 of the frame (within the frame information part 34) contains a representation (e.g. a value set to "0"), which means that the frame is signalled to other devices (to which the device sending the frame sent the frame on the network), and which has control over at least the interval of the frame (where no other devices are also sending) and means that the data payload will be sent at the same data rate as the standard data rate.

However, when required, and as part of the proposed protocol, there may be another type of frame, as shown in figures 3, 4 and 5, in which the control block 25 of the frame contains a different token (e.g. the value is not set to "0" but to, e.g., "1") and which is transmitted by the initiating device during the control block 25 and received by any and all devices within the network, the token indicating that there is a portion of the frame (payload) at a new data rate, which is higher than the rate used within the frame before the start of transmission of the payload.

The new data rate may be fixed by convention, or the new data rate may be indicated within a control block of the frame, or the data rate may be decoded using knowledge of the employed coding scheme and clock recovery, or the new rate determined by previous data communication over the network. The actual method of data rate determination and use will be described more later in this specification, and thus the protocol employing this configuration will be described.

Fig. 2 shows a frame transmitted using a standard data rate, comprising a header block 22, an address block 24, a control block 26 (containing a token 50), a data block 27 and a checksum block 28, all of which constitute a block 34, followed by a dummy block 30 and finally an acknowledgement block 32, which constitute a complete acknowledgement communication frame 35, as a transmitted message.

Each block in a frame may include zero or more slots and may appear in a different order in different protocols. The configuration of blocks within a frame may vary.

The acknowledgement block may be positive, indicating successful receipt and processing of the message, or negative, indicating some failure, and potentially including data indicating the cause of the failure.

For purposes of example only and not intended to limit the scope of the claimed invention, the frame shown in fig. 2 is a typical C-Bus network communication configuration, primarily because it uses dummy blocks that include a single dummy slot as a marker for the end of a series of blocks, but this is not necessary in other network communication configurations or protocols, and further, when a frame is preceded or followed by two consecutive dummy slots, the network will begin to operate again, wherein multiple devices will begin to compete for control of the network. In essence, the timing length of the dummy block comprising two consecutive dummy slots is equal to the idle medium determination period, which is the period of time during which all receivers of all devices perform network monitoring to determine if the medium (network) is busy, as achieved between devices that comply with and use the preferred protocol. Since there is no activity on the network during the time of two consecutive dummy slots, all receivers of all devices will know that the medium is not only not busy, but also available to send frames containing payloads of data located to one or more devices on the network from one or more transmitters of the one or more devices.

Common to most protocols is the way a device contends for control of the network for transmission. Thus, there are different periods of contention, not only when using a particular protocol, but also when using different protocols, which are used to determine that only one transmitter is transmitting on the network, i.e., the winning device, because all other devices that want to transmit are also receiving through their respective receivers and determining that they have received a signal while transmitting. The above description is but one of various bus contention methods used in one or more different protocols.

Thus, fig. 2 shows a frame transmitted using a standard data rate entirely, containing a data payload transmitted at the same standard data rate. The standard data rate in C-Bus during information transmission is 5405 baud rate, but the term standard is not intended to indicate that all network communication systems (other than C-Bus) transmit and receive at a particular data rate. It also does not indicate that there is only one data rate available to the network, as there are networks that can use more than one data rate, which is only possible if all devices use the one of the more than one data rate simultaneously, and if the data rate is changed the devices need to coordinate to use the one data rate. For purposes of understanding the configurations disclosed in this specification, the term standard or first data rate is used to represent a data rate that is common to all devices.

In the high speed setting block 37 of fig. 4 of this embodiment comprising a control block 25, in the control block 25, at least in this embodiment, there is a high data rate characterization 51 indicating that the remainder of the message or frame having this type of control block will comprise a portion in which data will be sent at the standard data rate or a higher data rate than that used in the previous portion of the message. This representation takes the form of a "1" bit high data rate representation 51 located within control block 25 of fig. 4 and incorporated within high speed setting block 37 of fig. 3, which distinguishes this frame from the standard low speed frame shown in fig. 2, in which control block 26 contains a "0" bit at the same point of the frame.

In fig. 3, the high speed setup block 37 is used to represent the combination of the header block 22, address block 24, control block 25 (containing the high data rate token 51) and checksum block 28 shown in fig. 4. Fig. 3 also contains a dummy block 30 following the high speed set block 37, the dummy block 30 being followed by a confirmation block 32, the purpose of both blocks being equivalent to the dummy block 30 and the block 32 shown in fig. 2.

Fig. 3 also shows

additional blocks

36 and 38 added after block 32, and contains a total of three "dummy blocks" 30 between

blocks

37 and 32, between

blocks

32 and 36, and between

blocks

36 and 38.

In the present embodiment, the dummy block 30 is a blank slot (excluding data) for indicating the end of the previous section before the next section of the frame starts. In some protocols, the use of these dummy blocks may not be necessary. In an example C-Bus network, the idle medium determination period is a dummy block including two or more consecutive dummy slots, and is a particular feature of the C-Bus embodiment. However, the idle medium determination period may be different in other protocols, but is always used after the last block of the frame is transmitted and received by the receiver, i.e. after the block 32 for the protocol with such an acknowledgement block. Then once the devices on the network determine that the bus is free, a bus contention period begins as multiple devices may begin transmitting, and eventually one of the devices will win. That is, the bus contention periods are very different in function, and may be very different in the actual time elapsed until the idle medium determination period.

In some protocols, a preamble block (not shown) may exist within or before the header block, but the preamble does not typically convey any information, but instead may be used to perform: recovering a clock; functions related to facilitating a contention scheme between more than one device, such as by including a priority determination bit or byte; and is used to warm up the clock recovery circuit in preparation for receiving the remainder of the frame that occurs after the preceding block.

Header block 22 may or may not be present and is not set to include information about the type of frame that follows, and may also provide priority information related to the message and how it should be treated by devices on the network, or the status of the frame.

The address block 24 is used to define one or more intended destination devices on the network for the frame. The address block may also provide information about the identity of the sending device so that a reply may be returned to the sending device.

The control block 26 is shown in the frame shown in fig. 2 and the control block 25 is shown in fig. 4. The control block contains information for the target device and/or all devices and their associated device configurations, which information relates to how the frame is to be interpreted. The block contains the result of the steps of a method in which the protocol may contain additional information such as an indicator that in one embodiment higher data rate data or standard data rate data is present in the subsequent portion of the frame. The indicator or other indicator may indicate an alternative coding method, an alternative checksum method and/or a length of the higher data rate data portion of the variable data rate frame.

The data block 27 comprises the payload of the message. In fig. 2, the data block 27 is part of a transmitted message block 34. In the case of fig. 4, the control block 25 includes an indicator that a higher data rate data block 36 (payload) follows as shown in fig. 3.

The checksum block 28 in fig. 2 and 4 is included for the convenience of the target device, providing an error detection code for the relevant portion of the transmitted frame. The algorithm for this code may be a simple sum or hash of the appropriate bit length or a cyclic redundancy check code, or any other error detection code.

The single low-speed message block 34 shown in fig. 2 and the high-speed setup block 37 in fig. 3 and 4 are used to represent the combination of

blocks

22, 24, 25/26, 27 (in the case of fig. 2 only) and 28; in fig. 4, where the set (information) frame part high speed setting block 37 contains a control block 25 comprising a high data rate representation 51 indicating that higher data rate payload data is present subsequently, the set frame part in this embodiment comprises the higher data rate setting block within the more commonly named frame information part.

In a C-Bus network, the acknowledgement block 32 (fig. 2 or 3) includes an allocated time period during which one or more receiving devices may transmit a code indicating that they have received the frame information portion high speed setting block 37 with or without error, and as described below, the devices transmit non-Negative Acknowledgements (NAKs) that contain additional information regarding the ability of each receiver to receive data at a particular data rate.

In a CSMA/CD network, during transmission of a frame, all devices on the network except for one device associated with the current transmission hold off (hold off) any pending transmission until a time after the end of the current transmission of the frame, which is at least a medium idle determination period (a period of time shorter than the period of at least two dummy blocks, as described earlier), and then start a bus contention period, as described earlier.

At the time the higher data rate setting block 37 and its acknowledgement block 32 complete, the bus contention period ends, and in CSMA/CD using CA, a collision avoidance duty should be implemented, thereby freeing the network for sending the higher data rate portions from CA-based timing constraints and allowing the use of higher signaling rates, which are closer to the broadcast network bandwidth (for broadcast messages) or to the point-to-point network bandwidth (for point-to-point messages, where point-to-point is device-to-device).

Devices that are not related to the transmission cannot or need not decode the message (except possibly for the fact that there is a higher data rate being transmitted, or as if there were no transmission on the network if the receiver was only able to receive a standard data rate), and these devices may determine the end of the transmission after the progress of the transmission. The device intended to receive the transmission transmits an appropriate data acknowledgement block 32 in the case of a standard (low) rate transmission; and an appropriate data acknowledgement block 38 (other than 32) following the additional higher data rate data block is sent and received. However, if devices not associated with the transmission are unable to decode the frame (because they do not detect data transmitted at a higher data rate), they continue to determine the busy state of the communication medium by other means, as described in this specification. In one case, if the odd parity or asserted check bits are implemented by the communication protocol, the presence of a transmission on the network may be detected by the presence of any data '1' bits, such as or by using padding bits within a frame as in the CANbus protocol. Thus, the step of sending a signal at a standard data rate so that all devices know that the network is busy is part of the method described in this specification.

Manchester encoding may be used, but is one of many available encoding mechanisms known to those skilled in the art, selected based on maintaining direct current (dc) balance or other such importance criteria for the network used. 7B/9B or 8B/10B coding schemes for higher data rate data coding are preferred, and by observing the transition of the signal over the communication medium for coding using these and possibly other schemes, the medium can be detected as busy, although if the higher data rate is much faster than the legacy (also referred to as "standard") data rate, as typically employed by designers in the art, low pass filtering in legacy receiver circuits of the device may produce higher data rate data that cannot be detected or identified from noise. Sending a "1" bit at the standard (low) transmission rate ensures that all legacy devices will detect the signal and conclude that the bus is a non-idle bus, and then new higher data rate data can be transmitted without ensuring further bit detection by these legacy devices.

Fig. 5 illustrates one embodiment applicable to a C-Bus network configuration in which the higher data rate payload 36 (fig. 3) is transmitted as a plurality of slots, but with the accompanying text contained in each transmitted slot: a bit of value '1' that is sent at the standard data rate to alert all devices on the network of the standard data rate to: the medium is not idle but busy and is under control of the device that is transmitting information. Fig. 5 illustrates a plurality of High Data Rate (HDR) slots including HS slot 1, HS slot 2, …, HS slot n, the last slot including an error detection code (e.g., checksum) with respect to the high speed payload data.

The detection of a busy communication medium as described above is part of the steps of the method and allows all devices not participating in the current communication to remain idle and not interfere with communication on the available communication medium.

As long as the criteria for preventing incorrect detection of an idle communication medium by legacy devices during the higher data rate portion of the frame are or have been met for a given protocol, such as in the example C-Bus where no apparently empty dummy block is at the legacy signaling rate and a synchronous clock is present, all other aspects of the communication within the frame can be freely changed to achieve extended performance.

In embodiments implementing Higher Data Rates (HDR), as long as a single bit within each HDR slot is implemented according to the strict timing rules of the protocol, the remaining time within each synchronization period may be freely used and encoded in any manner compatible with the constraints of the physical medium, as long as such encoding does not exceed the electrical limitations of the hardware for legacy data receiving devices and associated device configurations on the same network that are adapted to receive higher data rate signals.

Fig. 6 illustrates a possible encoding method that may be used in a protocol in which a data symbol 48 for a single '1' bit (shown as the negative going portion of the pulse just above the number "48", being a single '1' bit data symbol) follows a synchronizing clock symbol 46 (shown as the negative going portion of the pulse just above the number "46", being a synchronizing symbol) and shows its associated transition. Thus, the data symbols 48 are medium busy signals transmitted using a 'first' rate (also referred to as the standard rate), which is the data exchange rate used between the devices for communicating command and control data, rather than the subsequent higher data rate.

Thus, the remaining time period 40 within the standard data rate time period 42 (in this case, the synchronization signal) may be used for an appropriate data encoding method at a higher data rate than that used for standard data rate device communication. As shown in fig. 5, a plurality of such consecutive synchronization signals of the frame may be transmitted, with the higher data rate portion included.

Payload data transmitted at the higher data rate indicated in the frame information portion may also be decoded in the receiver of the device using a clock signal recovered from data transmitted at the higher data rate.

Fig. 3 shows a high-speed communication frame having a frame information part high-speed setting block 37 (high-speed setting block), a dummy block 30 and an acknowledgement block 32 transmitted at the standard data rate, but this time, in response to control information in the control block 25 within the frame information part high-speed setting block 37, an additional dummy block 30 and a high-speed data block (higher than the first rate (standard rate)) 36 are added to the frame. The high speed data payload block 36, which is part of a frame in which the higher rate data block communication is conducted at the new higher data rate, may be encoded in various ways, and the encoding may be described by some or all of the data encapsulated within the control block 25 of the frame information part high speed setting block 37.

The high speed data rate data block 36 includes a component that meets the busy medium rules according to the requirements of the legacy protocol (as described earlier by way of example, a '1' bit data symbol 48 is used within the period 42 of the synchronization signal shown in fig. 6), and also allows time to encode data appended to the portion of the frame sent using the legacy protocol (before which the high speed data block 37 precedes) in a manner defined by the control message in the frame information portion. The high speed payload data block 36 may also include the use of an error detection code such as a checksum or Cyclic Redundancy Check (CRC) as shown in fig. 5 to assist in detecting errors sent within the payload data block 36 and may be followed by a further dummy block 30 and a second acknowledgement block 38. Note that block 32 is followed by a first acknowledgment block that completes the transition to the transmission of block 37 in the presence of block 36 data, or is followed by negative acknowledgment and

negative blocks

36, 30 and 38. If the acknowledgement 32 is positive and is followed by block 36, block 38 is a second acknowledgement block, but only for the acknowledgement of block 36, and has a different format and thus a different meaning than the first acknowledgement block 32. The foregoing description is only one example of how to transmit higher rate data, as there are many different types of acknowledgements (positive and negative) that can be used to handle data transmission between devices.

During relatively high data rate communication within a frame, all compatible devices are preferably synchronized by the particular frame and/or by a synchronization clock that is always present on the communication medium. The synchronous clock provides only a timing reference and can therefore be generated by a "dumb" clock device located anywhere on the network.

While a non-smart clock is sufficient to provide synchronization of standard data rate communications and may be provided by different devices on the network, it is not accurate enough to provide synchronization of the higher data rate portion of the frame due to, for example, its physical remoteness, data rate effects such as signal propagation delays, etc. Thus, a better way to synchronize to the higher data rate portion may be a '1' bit data symbol 48 that is generated by the same device that sent the higher data rate frame and that has the same network propagation delay at the receiver as the remaining higher data rate data portion of the frame.

For the design of a communication protocol utilizing CSMA/CD and/or CA using higher data rate setting blocks, it is preferable to consider the physical characteristics of the network, such as maximum bandwidth within the known maximum physical length of the two-wire communication medium, not only between the devices that are electrically farthest apart, but also between the devices that are electrically close, based on the topology rules of the network, cable transmission, network and device impedance, etc. Predetermining and using these and other correlation characteristics reduces the likelihood and/or chance of timing errors that may occur if the range is exceeded or unknown. Furthermore, it is preferred that the high data rate control block (25) of the device requesting the variable data rate (relatively higher data rate) protocol frame contains sufficient information to allow the receiving device to accept the appropriate information for the appropriate data bit rate and message length shown in fig. 7, which also is shown in fig. 7, including a message type block 70, a message type block 71, a control block length block 72, a high speed data rate block 73, a high speed data encoding type block 74, a higher data rate length block 75, and an error detection code (checksum) method block 76 to be used at the higher data rate. Some or all of the other information within the high speed control block 25, except for the high data rate indicator 51, may optionally be fixed by convention, in which case such information need not be specified and thus may be omitted. These fields, if included, need not appear in the same order as described, but may be ordered freely according to the needs of the protocol designer, so long as compatibility with legacy (low speed) devices is maintained.

The high speed data rate is not necessarily a fixed preset data rate, as the device may be capable of receiving/transmitting two or more data rates, so that the initiating device may include data 73 representing the data rate at which data is to be transmitted. Some devices may be able to automatically detect and adapt to any received data rate. Thus, the data rate is considered to be variable, but typically does not vary within a frame, but may vary from frame to frame, while being substantially deterministic for a particular frame.

In the case where the higher data rate setting block includes information about the proposed higher data rate transmission, the receiving device may respond with a positive acknowledgement 32, or with one or more of several types of negative acknowledgements including, but not limited to, negative acknowledgements meaning "unsupported higher data rate", "supported higher data rate, but not as high as indicated high speed setting block", "supported higher data rate, but not as high as indicated setting block, with a particular maximum data rate", etc.

In one embodiment, a variable data rate (relatively high data rate) block period is used by a device positioned for a receiver during the normal data rate portion of the frame.

Fig. 8 shows an exploded view of the acknowledgement block 32 of fig. 3, the acknowledgement block 32 being negative in a configuration of a device capable of receiving data transmitted at a higher rate (higher than the standard rate), the acknowledgement block 32 including in part 82 a code indicating that the device understands that higher speed is being transmitted but the device is unable to communicate at the particular data rate. As shown in fig. 8, bits N84 through 286, bits 188 and finally bits 090 are the fastest data rates at which the devices can communicate as shown in fig. 9. fig. 9 shows that if each device is unable to receive the particular data rate transmitted, each device makes a '1' bit contribution to the code in a multiplexed manner, depending on the maximum supported high speed data rate for each device. In the case where the '1' bit dominates the bus, the result code sent on the network will represent the maximum speed at which a high speed message can be sent and successfully received. For example, fig. 10 shows a table representing an example register of data that allows a transmitting device to determine what is the maximum data rate that all devices (responding with an ACK or NAK) can accept to transmit a payload in the same frame by checking the code in the negative acknowledgement. Thus, as shown in fig. 9, reception of '000001' means that, for example, 24 times the standard data rate can be used, since all devices can receive data at that rate, while reception of '000011' means that the maximum data rate for transmission is 20 times the standard data rate, and so on, until reception of '111111' means that the maximum data rate that can be received by all devices located in block 27 is 8 times the standard data rate. This information can be used by the sending device to simply send the high speed data payload block 36 at the rate indicated in the negative acknowledgement register, provided that all the addressed receiving devices have also read the contents of the negative acknowledgements, or, if the acknowledgement block 32 is positive as expected, to simply retransmit the high speed set block with the high speed data rate indication at the rate indicated in the negative acknowledgement block, and then send the high speed data payload 36 at that rate.

The type of data that may be provided during the variable data rate (relatively higher data rate) communication blocks of a frame may include any useful data type, including but not limited to normally operational data, firmware upgrade and configuration data of one or more devices or associated equipment, bulk data transfer, or high bandwidth consumption information such as audio or video to/from a particular device.

The communication requirements for relatively low data rate communications within the network may also be met and information encoded at the same time at a higher rate so that higher data rate-tolerant devices may receive and accept higher data rate data while other devices operate at their own relatively low data rates, whereby both types of devices may coexist in the same network.

For each byte of relatively low data rate data in a byte-oriented network protocol, such as the protocol described as an example here exemplified by the schneider C-Bus protocol, if a higher data rate communication can start symbol synchronization for each byte and insert one valid low data rate bit into each byte, that byte can be recognized by legacy devices as a valid communication, then according to the protocol, when in fact no legacy devices are transmitting and the devices that are using a variable data rate (relatively high data rate) have uninterrupted access to the network, the devices cannot participate in the higher data rate exchange, further and necessarily the devices simply consider the legacy network busy.

Fig. 6 shows slots in a byte oriented protocol, such as the schneider C-Bus protocol, showing that the clock timing for the lower data rate byte time 42 is the same as the clock timing for the lower data rate communication over the network, including the synchronous clock symbol 46. In an embodiment of the invention, a synchronous clock 46 (which may be sent by the same or a different device on the network to the remainder of the slot) is followed by a single data bit for data symbol 48 to be received by all devices on the network, sent by the sending device operating according to a normal data rate, and included to indicate to all other devices in the network that the holding medium is busy signal. Further, in the present embodiment, the lower speed data bits for the data bit symbols 48 are followed by the data block 40 transmitted at the higher data rate for the remaining time of the clock synchronization signal period 42 inserted in the remaining time period 40. Since the collision avoidance duty of the communication device is complete at the time the high speed data block is sent onto the bus, the edges of the data bits for the data symbols 48 can be made to transition harder, allowing them to be used as a synchronization signal for the data in the remainder of the slot. The signaling rate of the high-speed payload data in the slot may be set according to one or many factors, including but not limited to the actual network physical characteristics of the communication medium (such as two wires) having a known maximum bandwidth that may operate, for example, within a known maximum physical length of the communication medium. If these functional limitations are known, then a data rate of the one or more higher data rates may be predetermined for use within the network protocol because both broadcast transmissions and point-to-point transmissions may be transmitted by the winning device at the higher data rate.

The actual network bandwidth between the transmitting device and the receiving device may be learned by the transmitter over successive transmissions based on the success rate relative to the previously transmitted data rate by using the actual broadcast bandwidth (given the lower limit of higher data rate signaling that should always be successful) and the maximum signaling rate that the transmitter is configured to use. A higher data rate transmission negatively acknowledged by the receiver with an indication of unsuccessful reception (for which an acknowledgement of "support for higher data rate" was received earlier in the transmission) is reattempted as is, or at a lower data rate. Once a successful transmission and acknowledgement are received, the successfully transmitted data rate can be used as a basis for subsequent transmissions using a learning algorithm that adaptively speeds up and slows down based on prevailing network conditions.

The proposed higher data rate may be part of a bus contention period, such that, as previously described, the proposed higher data rate may be used to determine a winning transmitter, i.e., the fastest transmitter overrides a slower transmitter for one or more receivers capable of receiving at a higher data rate. The protocol in such a configuration includes data representing the highest data rate proposed at which the winning device can transmit data during the bus contention period of the frame and only the receiver that received the highest data rate data will provide an acknowledgement.

During the time period 40 within the slot, the transmitter of the device is able to transmit communications at any data rate, the only limitation being the physical characteristics of the network between the transmitting and receiving devices, not any convention for compatibility with existing devices on the network.

During time period 40, encoding standards such as Manchester 4B/5B, 8B/10B using an appropriate codebook or any other appropriate form of line encoding used in other sequential transmission schemes such as Ethernet may be used to achieve higher data rates and still preserve the direct current (dc) balance of the network. For other cases where DC balance is not important, other mechanisms will be used.

The information provided in this disclosure may be applied to many packet switched baseband signaling networks to achieve a significant increase in data throughput compared to the typically fixed, relatively low data rates of these networks. In particular, application of the information disclosed herein to schneider C-Bus systems and protocols can deliver data at a rate at least 6 times the normal data rate, and typically for 24 times or more between adjacent devices on a small or large network, the actual rate used can vary depending on the predicted and actual number of successes in the transmission to/from the different devices.

Other types of networks may have (as disclosed in embodiments described herein) different periods of time during which higher data rate frame segments may be present, but in most cases (as can be readily identified by those skilled in the art in understanding the present disclosure), once a period of operating normal data rate has elapsed, which is a period set to contend among the devices to determine which of them has exclusive access to the communication network (bus), there is an opportunity to effect relatively higher data rate communications from the originating device to one or more other devices in the network when it can be assured that only a single transmitter is transmitting.

In some networks that use time division multiplexed communication periods with variable data rate setting frames, and when the transmission of data is at a higher data rate, there is a time division multiplexed communication period with time slots for each device synchronized by a single clock referenced by the network.

Setting up a protocol to use and identify bus contention periods for legacy devices while operating at a relatively low data rate enables all devices to participate in the network while enabling not only the selection of different communication rates used by compatible devices, but also the introduction of a more robust error detection protocol during periods of relatively higher data rates, thereby enabling larger messages to be sent at the same time as when legacy systems would be used for smaller messages.

It will be apparent to those skilled in the art that it may be desirable to ensure that the encoded data in the higher data rate portion of the frame should not be confused with other valid signals on the network, including the synchronous clock signal, if present. Thus, the encoding mechanism (such as the preferred 8B/10B) should be implemented using a codebook that, in combination with the minimum higher data signaling rate selected, in addition to maintaining the correct direct current (dc) balance of the signal, ensures that the high data rate data maintains a sufficient transition rate so that it never goes wrong for the synchronous clock pulses, thereby ensuring that legacy (low data rate) devices never get confused about the position of the synchronous clock and potentially initiate communication outside of synchronization.

It is also expected that the receiver and transmitter hardware of existing devices will not require any modification and yet will be compatible with networks having higher data rate data frames, but will not need to be able to decode them unless they are upgraded, or if they are updated, they may only be able to decode lower data rates within the range of higher data rates at which newer devices can decode and/or transmit.

The described protocol can be used by the schneider C-Bus protocol and its legacy devices and new higher data rate devices, but it is not limited to this network system, but may find application in KNX, CANbus, DALI and other related network system protocols.

In, for example, a CANbus network, if a device wishing to transmit finds a shared medium in an idle state, it waits for the next slot and starts an arbitration phase by sending a frame start bit. At this point, each device having a message to send (e.g., the message may be placed in a peripheral register called TXObject) may start a race for granting access to the shared medium by sending the identifier (priority) bits of the message in an arbitration slot in series, one bit for each slot starting with the most significant bit. The conflict between the identifier bits is resolved by a logical AND algorithm AND if the device reads its priority bits on the medium without any change, it realizes that it is the winner of the contention AND it is granted access to send the remainder of the message while the other devices switch to listening mode. In fact, if one of these bits changes when it is read back from the medium, this means that there is a higher priority (the reserved bit) contending for the medium, and thus the message is withdrawn. In such a configuration, it may still be possible to include data indicative of the data rate of the data provided by the apparatus at a location within the frame transmitted from the apparatus that is between the start of the frame and the portion of the frame at which the data is transmitted at the higher data rate, and by way of example, after the keep-medium-busy signal transmitted at the first data rate, it may be that a keep-medium-busy signal is transmitted with each block of payload data or some other configuration.

Claims

1. A method of communicating data in a packet switched baseband signalling communication network having a plurality of devices, wherein each device comprises at least a data transmitter and a data receiver capable of transmitting and receiving frames comprising payload data at least at a first data rate, said method comprising the steps of:

transmitting, by a transmitter of an apparatus of the plurality of apparatuses, data at a first data rate in a portion of a frame indicating that payload data to be subsequently transmitted in the frame is to be transmitted at a higher data rate than the first rate; and

during transmission of payload data at a higher data rate, a keep medium busy signal is transmitted by the transmitter of the device at a first data rate indicating to other devices that the network is in use.

2. The method of claim 1, wherein the frame includes a frame information portion, the method further comprising the steps of:

at the receiver of the frame transmitting device, a representation of the highest data rate that the receiver of each device is capable of receiving is received from the transmitter of the one or more devices, wherein the representation is included in an acknowledgement sent back to the receiver of the device in response to receipt of at least a portion of the frame information portion of the frame.

3. The method of claim 2, further comprising the steps of:

determining, from the received one or more acknowledgement characterizations, that the higher data rate is to be used when transmitting payload data.

4. The method of claim 1, further comprising the steps of:

transmitting payload data using the higher data rate; and

the representation of the higher data rate is placed in a frame before the payload data is transmitted at the higher data rate.

5. The method of claim 1, further comprising the steps of:

using an error detection code to transmit payload data at the higher data rate; and

before transmitting payload data at the higher data rate, a representation of an error detection code is placed in the frame.

6. The method of claim 1, further comprising the steps of:

using a coding mechanism to transmit payload data at the higher data rate; and

before transmitting payload data at this higher data rate, a representation of the coding scheme is placed in the frame.

7. The method of claim 1, wherein the device employs a network device that uses a carrier sense multiple access/collision detection protocol.

8. The method of claim 7, wherein the carrier sense multiple access/collision detection protocol also uses collision avoidance.

9. The method of claim 1, wherein the transmission of the payload data at the higher data rate uses manchester encoding.

10. The method of claim 1, wherein the transmission of data at said higher data rate uses 8B/10B coding.

11. The method of claim 1, wherein the sending of data at the higher data rate is used to send one or more of the group of: firmware for updating the device; configuration parameters of devices on the network; batch data, audio; or video information.

12. The method of claim 1, wherein during transmission of data at said higher data rate, there is a time division multiplexed communication period having time slots for each device synchronized by a single synchronous clock referenced by the network.

13. The method of claim 1, wherein the keep-medium-busy signal is transmitted before some or all of the higher data rate data within a slot and is used by the transmitting and receiving device as a synchronization signal for reception of the higher data rate data for some or all of the remainder of the slot.

14. The method of claim 1, further comprising the steps of:

in a receiver of the apparatus, payload data transmitted at the higher data rate characterized in the frame information portion is decoded using a clock signal recovered from data transmitted at the higher data rate.